Phenotyping OSAH patients during wakefulness.

PURPOSE: Although currently there are simplified methods to measure the pathophysiological traits that stimulate the occurrence and maintenance of obstructive sleep apnea-hypopnea (OSAH), they remain difficult to implement in routine practice. This pilot study aimed to find a simpler daytime approach to obtain a meaningful, similar pathophysiological phenotypic profile in patients with OSAH. METHODS: After obtaining diagnostic polygraphy from a group of consecutive patients with OSAH, we performed the dial-down CPAP technique during nocturnal polysomnography and used it as reference method. This allowed assessment of upper airway collapsibility, loop gain (LG), arousal threshold (AT), and upper airway muscle gain (UAG). We compared these results with a daytime protocol based on negative expiratory pressure (NEP) technique for evaluating upper airway collapsibility and UAG, on maximal voluntary apnea for LG, and on clinical predictors for AT. RESULTS: Of 15 patients studied, 13 patients with OSAH accurately completed the two procedures. There were strong (all r2 > 0.75) and significant (all p < 0.001) correlations for each phenotypic trait between the measurements obtained through the reference method and those achieved during wakefulness. CONCLUSION: It is possible to phenotype patients with OSAH from a pathophysiological point of view while they are awake. Using this approach, cutoff values corresponding to those usually adopted using the reference method can be identified to detect abnormal traits, achieving profiles similar to those obtained through the dial-down CPAP technique.

In adatom diffusion on In(x)Ga(1-x)As/GaAs(001): effects of strain, reconstruction and composition.

By using density functional theory (DFT) calculations of the potential energy surface in conjunction with the analytical solution of the master equation for the time evolution of the adatom site distribution, we study the diffusion properties of an isolated In adatom on In(x)Ga(1-x)As wetting layers (WL) deposited on the GaAs(001). The WL reconstructions considered in this study are, listed in the order of increasing In coverage: c(4 × 4), (1 × 3), (2 × 3), α(2)(2 × 4) and ß(2)(2 × 4). We analyze the dependence of the diffusion properties on WL reconstruction, composition and strain, and find that: (i) diffusion on the (2 × N) reconstructions is strongly anisotropic, owing to the presence of the low barrier potential in-dimer trench, favoring the diffusion along the [Formula: see text] direction over that along the [110] direction; (ii) In diffusion at a WL coverage θ = 2/3 monolayers (ML; with composition x = 2/3) is faster than on clean GaAs(001) c(4 × 4), and decreases at θ = 1.75 ML (x = 1; e.g. InAs/GaAs(001)); (iii) diffusion and nucleation on the (2 × 4) WL is affected by the presence of adsorption sites for indium inside the As dimers; (iv) the approximation used for the exchange-correlation potential within DFT has an important effect on the description of the diffusion properties.

[National study of drug habits in Uruguay]. / Estudio nacional de hábitos tóxicos en el Uruguay.

The results of a prevalence study of alcohol abuse and drugs use in the general population of the República Oriental del Uruguay are showed here. A national household sample was drawn from the most important urban areas and 2500 persons, aged between 15 and 65 years, were selected and interviewed. Illicit substances use (include use of any of the following: marihuana, cocaine, inhalants, hallucinogens) reached 4.5% for the lifetime prevalence period, 1.1% in the last twelve months and 0.7% for the last thirty day. Twenty percent of the sample classified for tobacco dependence, and alcohol abuse, in the last 30 days, was 19.5%. Significant associations, by sex and age, were found.

[Patterns of drug abuse among youngsters of upper social class]. / Patrones del uso de drogas en jóvenes de clase alta.

Street drug use, and alcohol abuse among young adults from a high social class range were studied in the posh seaside resort of Punta del Este (Uruguay) during the (austral) summer vacation (February 1993). In this connection, an anthropological methodology was applied: Four young people were trained in systematic record and observation technics abilities. Results suggest two clearly defined social-cultural patterns with regard to both cannabis, and cocaine use. Both patterns take place within a social environment agreeable to drug use as well as strongly connected with social interaction ways peculiar to high-class youth.

Characterization of bioacceptable carbon materials.

Bioacceptable carbon films deposited with a new low temperature technique have been investigated using Raman and X-ray photoelectron spectroscopy. Our results reveal a substantial similarity between the low temperature deposited film and the well-known bioacceptable low temperature isotropic (LTI) pyrocarbon. The Raman spectra, as well as the larger density and oxygen content in the bulk, lead to the speculation of the presence of the common tetrahedral bonds in these materials.